How to adjust the screws of a carburetor?

To do this, tighten the screw to be fully adjusted without forcing and unscrew to the basic setting.

• The idle screw will be adjusted so that the engine is at stable engine speed.

The basic setting of a WT-603 carburetor:

• HIGH screw (H): 1tr 3/8.
• LOW screw (L): 1tr 1/4.

The basic setting of a WT-990 carburetor:

• HIGH screw (H): 1 1/2 tr
• LOW screw (L): 1 tr

The basic setting of a WT-1107 carburetor:

• HIGH screw (H): 1 tr 5/8,
• LOW screw (L): 1 tr 1/8.